2/8/12 - virginianotill.com

2/8/12

1

Deep Tillage for Corn: Yes? No? Maybe??

Wade Thomason Extension Grain Specialist,

Virginia Tech [email protected]

Compaction Plow Pan

Non-Compacted Sub-Surface

Non-Compacted Ap

Zone where traffic pan has been disrupted by “ripping”

Disk Pan

Soil Level

Soil Level

IPM Images, JG Davis

Identification of Compaction

•  Platy or weak structure, or a massive condition

•  Greater penetration resistance •  Higher bulk density •  Restricted plant rooting •  Flattened, turned or stubby plant roots

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2

Effect of Compaction on Permeability

Compaction

Perm

eabi

lity

C. Lawrence

Depth of Compaction as Soil Moisture Increases

•  Tire size 11 x 28, load 1,650 lbs, pressure 12 psi

Depth of Compaction as Axle Load Increases

•  Tire pressure remained at 12 psi for all tire sizes

TRUE OR FALSE?

All other factors being equal, a soil will typically become more susceptible to

compaction over time tillage frequency and intensity increase.

2/8/12

3

TRUE OR FALSE? All other factors being equal, a soil with

higher organic matter content will be more resistant to compaction.

TRUE OR FALSE?

All other factors being equal (total weight, horsepower, etc.), a 4WD tractor will cause less compaction than a 2WD

tractor.

What we want to see?

•  Composition of “Ideal” Soil – 50% solids

•  45% mineral material •  5% organic matter (SOM)

– 50% pore space •  25% water-filled •  25% air-filled

Complexity of soil pore system

•  Good soil pore system is COMPLEX!

How many tillage passes would it take to create / repair the soil pore system? What tillage tool(s) would you use?

Aggregation

•  Aggregate stability: – Ability of aggregate to resist

breakup by •  Water

– Raindrop action, surface flow, dissolution, etc.

•  Mechanical action –  Tillage, compaction, etc.

•  SOM is the “glue” that holds together soil aggregates.

Deep Tillage

•  Loosened Zone and Resulting Root Pattern

•  Subsoiler Operation in Deep Sandy Soils

•  What are we talking about?

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4

Deep Tillage?

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5

An old question: If I rip my fields with a no-till subsoiler before

planting corn, will it put more grain in the tank???

An unfortunate answer: It depends…

Treatment Yield (bu/A) Difference (bu/A)

Ripped 133 +5

Not Ripped 128

A “Shotgun” Approach Probably Won’t Pay Off:

Effect of Deep Ripping on No-till Corn Yield, Combined Analysis of 25 Plots, 1997 - 2008

Will this cover your costs, plus a little profit?

Corn Yield Response to Ripping, 25 Plots, 1997 - 2003

W.E

. Ste

vens

, Ess

ex, 2

002

(Kem

psvi

lle)

W.E

. Ste

vens

, Ess

ex, 2

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(Atle

e)

Five

L, W

estm

orel

and,

200

3 (e

ndro

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V. &

R. D

avis,

New

Ken

t, 20

01 (A

ltavi

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D. &

C. D

avis,

New

Ken

t, 19

97

V. &

R. D

avis,

New

Ken

t, 20

01 (C

onte

toe)

R. R

ando

lph,

New

Ken

t, 19

99

W.E

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vens

, Ess

ex, 2

000

H. C

hand

ler,

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g &

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en, 2

000

R. E

llis,

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x, 1

999

J. Be

nton

, Mid

dles

ex, 1

999

W.E

. Ste

vens

, Ess

ex, 2

000

D. D

avis,

New

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t, 20

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C. R

ich,

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ter,

2000

C. R

ich,

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en, 1

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ll, M

iddl

esex

, 199

9

R. R

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New

Ken

t, 19

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H. C

hand

ler,

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g &

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en, 1

999

W.E

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vens

, Ess

ex, 2

000

V. &

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avis,

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Ken

t, 19

99

R. L

ewis,

Mid

dles

ex, 1

999

W.E

. Ste

vens

, Ess

ex, 2

000

D. &

C. D

avis,

New

Ken

t, 19

99

12 17

-13

+29+17

-22

+16+14+12+11+9+8+8+5+3+3+3+3+3+10-4

-25

0

25

50

75

100

125

150

175

200

225

250

Cor

n Y

ield

(bu/

acre

@ 1

5.5%

)

Ripped (avg. 133 bu/A)

Not Ripped (avg. 128 bu/A)

Yield change due to ripping (avg. +5 bu/A)

+12+11+7-1 -1

Five

L, W

estm

orel

and,

200

3 (S

tate

)

W.E

. Ste

vens

, Ess

es, 2

002

(Tet

otum

)

Can We Predict Which Fields to Rip?

•  Maybe •  Clues from Naderman’s work at NC State:

– Penetrometer alone not great predictor… – History of field

•  Amount of known compaction; •  Size and type of equipment; •  Amount of traffic when wet; •  Etc.

Which Fields? (cont.) – Soil type:

•  Tendency to compact; •  Depth of layer that tends to compact; •  Water-holding capacity below compaction

zone; •  Etc.

– Ripping technique: •  Timing of ripping; •  Amount of traffic between ripping and planting; •  Placement of seed in relation to ripper track; •  Etc.

Subsoiling Recommendations ROW CROP – N.C.S. data

Group I §  15 inches (A+E) light sandy coastal plain soils §  Profitable, practical, effective in increasing corn yields §  Less dramatic, but positive effects on soybeans

Group II §  10 – 15” (A+E) light sandy coastal plain soils §  Susceptible to forming thin, but dense traffic pans §  Still effective if “ripped” only as deep as lower E horizon

Group III §  Dark, Mineral Soils, restricted drainage, C.P. §  Results based on medium to course textures §  Avoid ripping in tight, clayey subsoils

Group IV §  Upland Soils, Piedmont (clayey Subsoils) §  Limited response when “ripping” in Spring

2/8/12

6

Ranking Soil Types – NCSU

•  Based on texture, subsoil depth, drainage •  Most likely:

Kempsville, Bojac, Wickham, Emporia, State, Altavista*, Suffolk, Rumford, Tetotum

•  Least Likely: Tarboro, Eulonia, Eunola*, Conetoe, Tomotley,

Slagle, Daleville, Myatt, Seabrook

Corn Yield Response to Ripping, 25 Plots, 1997 - 2003

W.E

. Ste

vens

, Ess

ex, 2

002

(Kem

psvi

lle)

W.E

. Ste

vens

, Ess

ex, 2

002

(Atle

e)

Five

L, W

estm

orel

and,

200

3 (e

ndro

w)

V. &

R. D

avis,

New

Ken

t, 20

01 (A

ltavi

sta)

D. &

C. D

avis,

New

Ken

t, 19

97

V. &

R. D

avis,

New

Ken

t, 20

01 (C

onte

toe)

R. R

ando

lph,

New

Ken

t, 19

99

W.E

. Ste

vens

, Ess

ex, 2

000

H. C

hand

ler,

Kin

g &

Que

en, 2

000

R. E

llis,

Esse

x, 1

999

J. Be

nton

, Mid

dles

ex, 1

999

W.E

. Ste

vens

, Ess

ex, 2

000

D. D

avis,

New

Ken

t, 20

00

C. R

ich,

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uces

ter,

2000

C. R

ich,

Kin

g &

Que

en, 1

999

R. R

usse

ll, M

iddl

esex

, 199

9

R. R

ando

lph,

New

Ken

t, 19

99

H. C

hand

ler,

Kin

g &

Que

en, 1

999

W.E

. Ste

vens

, Ess

ex, 2

000

V. &

R. D

avis,

New

Ken

t, 19

99

R. L

ewis,

Mid

dles

ex, 1

999

W.E

. Ste

vens

, Ess

ex, 2

000

D. &

C. D

avis,

New

Ken

t, 19

99

12 17

-13

+29+17

-22

+16+14+12+11+9+8+8+5+3+3+3+3+3+10-4

-25

0

25

50

75

100

125

150

175

200

225

250

Cor

n Y

ield

(bu/

acre

@ 1

5.5%

)

Ripped (avg. 133 bu/A)

Not Ripped (avg. 128 bu/A)

Yield change due to ripping (avg. +5 bu/A)

+12+11+7-1 -1

Five

L, W

estm

orel

and,

200

3 (S

tate

)

W.E

. Ste

vens

, Ess

es, 2

002

(Tet

otum

)

What Could Be Going Wrong? •  Inaccurate soil maps •  Measuring compaction or ripping at wrong soil

moisture conditions •  Wet Years – Excess Leaching of N •  Dry Years – “Mole Holes” •  Wrong Depth •  Seed Placement •  Time of ripping •  Traffic after ripping (esp. wet ground)

•  What are we talking about? •  Why would we consider doing it? •  Effect of compaction on corn yield •  How to do it? •  When to do it?

2/8/12

7

Targeted Tillage

•  Target Spatially – Between fields

•  Don’t assume all fields need ripping

– Within fields •  Focus on headlands, hot spots •  In-row is the way to go!

Targeted Tillage

•  Target Vertically – Probably most important use of penetrometer

•  Once you’ve decided to rip, determine right depth

– Do not assume deep tillage needed! •  Real world example:

– Owned a new tool capable of ripping to 16” –  Scouting with penetrometer showed hard pan was only 4

to 6 inches deep in field with long-term history of disking

Targeted Tillage

•  Target Timing –  If goal is to maximize shatter

•  Run when soils are dry soils (fall)

–  If goal is to minimize recompaction •  Run after all other preplant traffic (spring)

Thank You!